1. Field of the Invention
This invention relates generally to a pattern matching method, and more particularly to a novel pattern matching method in which, upon achieving a pattern matching by scanning a picture screen consisting of a plurality of picture elements arranged, for example, in row and column directions, information of a pattern to be recognized is compressed to perform a superior pattern matching.
This invention relates also to an apparatus for carrying out the above pattern matching method.
2. Description of the Prior Art
In prior art pattern recognition techniques, a pattern such as a letter, picture image or the like on a two dimensional picture screen is divided into a number of picture elements which are arranged in a matrix. An electrical signal or information corresponding to the light image of a pattern, which is to be recognized and projected on the screen, is produced from the picture elements in response to the pattern, and correlation between the extracted electric signal and a basic or reference electrical signal or information provides the pattern recognition.
In this case, various arrangements to convert the light intensity projected onto the picture elements into an electrical amount are known in the art, such as use of rotary discs, utilizing spot scanners, using pickup tubes, single line or two dimensional arrangement of photo-electric elements, etc. Further, as for the methods of scanning, various methods are known such as: (1) sequential scanning like a television camera, (2) right angled direction scanning of a single or a plurality of photo-electric elements, and (3) a parallel data extraction method from a two dimensional matrix of photo-electric elements, etc.
Now, supposing that the scanning time per element is constant, the total element scanning time is naturally longer in the sequence of the above methods (3), (2) and (1) in that order. That is, in the case of simultaneous parallel processing as method (3) above, the scanning time can be the shortest, but special circuitry is required to simultaneously process the data from each picture element, so that the circuitry becomes complicated.
Accordingly, in the case that the number of picture elements, which are arranged in matrix, are limited to a small number such as for optical character reading, the above mentioned method (3) can be placed into practice. However, when a number of picture elements become involved such as the case of pattern recognition, the realization of the method (3) accompanies extreme difficulties.